Seat cushion body and method of producing a seat cushion body

ABSTRACT

A seat cushion body and method of producing the same are provided. In a method of producing a seat cushion body, fiber material is inserted into a mold. Heat is supplied to the fibers to cause thermal activation of binding fibers, so as to effect thermal cross-linking. The resulting seat cushion body includes a resilient portion formed from the fibers and having a fiber orientation along a main load direction of the seat cushion body. The seat cushion body may include at least one further portion formed from the fibers, which has a fiber orientation and/or a density different from the fiber orientation and/or different from a density of the resilient portion. The resilient portion and the at least one further portion may be integrally formed from the cross-linked fiber material as a unitary body.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase application filing ofInternational Patent Application No. PCT/EP2011/003981, filed Aug. 9,2011, which claims the benefit of and priority to European PatentApplication No. 10008329.4, filed Aug. 10, 2010, the entire contents ofeach of which are incorporated herein by reference.

The invention relates to a seat cushion body and a method of producing aseat cushion body. The invention relates in particular to a seat cushionbody formed from a fiber material and a method of producing a seatcushion body from a fiber material.

Foams, such as polyurethane (PU) foams, are widely used as fabricbackings for seats, such as for vehicle interior materials in thetransportation industry. The foams are adhered to the backs of textileface materials. These foam backed composites have a cushion effect whichcan offer comfort or a luxurious feel in contact areas.

There are drawbacks to using polyurethane foam as cushioning materialfor seats. For example, the polyurethane foam backed material can emitvolatile materials which contribute to ‘fogging’ of vehicle or housinginteriors, and the foam itself may oxidize over time leading to a colorchange in the material. Recyclability is also an issue which has to beaddressed.

For these and other reasons, there is a continued need for anothermaterial that would provide cushion properties similar to the ones offoam materials at similar costs. One class of materials which hasreceived attention in this regard is nonwovens, for example polyesternonwovens. These materials can provide a suitable backing to many facefabrics. To date, however, in order to obtain cushions of a sufficientthickness, an economically deficient amount of material was required.

Methods of producing mats of perpendicular laid, thermally bondednonwovens, including air laid and “Struto” nonwoven techniques, havestrived to provide a cushion with an economical and weight advantage toprevious nonwoven technologies. These techniques orient the staplefibers into a vertical position and allow increased material thickness.However, the fiber material usually has to be heated plural times toproduce the sheet, and additional processing is required to form acushion body having a thickness and cushion properties satisfactory forseating purposes. This adds to the complexity and costs of the producedcushion body. Further, for a cushion body formed by joining pluralpre-formed mats produced using the Struto technique, the use ofcross-linking fibers in forming the mat may cause problems in downstreamprocesses due to reorientation when the mats are heated in downstreamprocesses such as molding or contouring. Combining a mat produced usingthe Struto technique with another mat produced using the Strutotechnique, or with other sheet-like materials, in a stacked structuremay also give rise to problems associated with the structural integrityat the interface between different mats or sheets of material. Suchstacked structures of joined mats may be prone to water ingress orstructural damage at their sides. Layering sheets produced fromdifferent materials may frequently be unavoidable to accommodate thedifferent requirements imposed on the surface of the cushion body, whichis expected to provide adequate backing for a cover material, ascompared to the requirements imposed on other portions of the cushionbody which provide resiliency upon exertion of a force along a main loaddirection.

In view of the above, there is a continued need in the art for a seatcushion body and a method of producing a seat cushion body which addresssome of the above needs. There is in particular a need in the art for aseat cushion body and method of producing the same which offers weightadvantages over existing PU foam cushion bodies, which provides goodbreathability and ventilation and which attains comfort characteristicscomparable to the ones of PU foam cushion bodies. There is also a needin the art for a seat cushion body which can accommodate different zoneswhich are formed from a fiber material, while mitigating the problemsassociated with stacked material layers. There is also a need in the artfor a method which allows such a seat cushion body to be formed withoutrequiring pre-formed sheets of perpendicular-laid nonwovens to be joinedto each other.

These and other needs are addressed by a seat cushion body and a methodof producing a seat cushion body as defined by the independent claims.The dependent claims define embodiments.

According to an embodiment, a seat cushion body formed from thermallycrosslinked fiber material is provided. The fiber material includesfibers of at least two different types. The seat cushion body has a mainload direction and comprises a resilient portion formed from the fibers.The seat cushion body has a fiber orientation along the main loaddirection. The seat cushion body comprises at least one further portionformed from the fibers, the at least one further portion beingdistinguished from the resilient portion with regard to at least one offiber orientation or fiber density. The resilient portion and the atleast one further portion are integrally formed from the cross-linkedfiber material.

In the seat cushion body, the resilient portion having a fiberorientation directed along the main load direction, which is typicallyorthogonal to the major face of the seat cushion body, provides desiredresiliency characteristics and a soft touch feeling. The weight requiredto attain a desired cushion characteristics may generally be reduced ascompared to a PU foam. Further, good breathability and ventilation isobtained. The at least one further portion having a density differentfrom a density of the resilient portion and/or a fiber orientationdifferent from a fiber orientation of the resilient portion allows theseat cushion body to address the various requirements imposed ondifferent portions of a seat cushion body, such as by providing adequatebacking for a cover material at the surface of the seat cushion body.With the resilient portion and the at least one further portion beingintegrally formed from the fiber material, a seat cushion body isprovided which is homogeneous in the sense that it does not have to beformed from separate material layers which are subsequently joinedtogether. The drawbacks associated with such structures can thereby bemitigated.

In the resilient portion having the fiber orientation, the fibers have apreferential direction corresponding to the main load direction. Ofcourse, not all fibers will be oriented along the main load direction inthe resilient portion, due to statistical fluctuations, variations infiber shapes and the presence of cross-linking fibers. However, thepreferential direction of the fibers in the resilient portioncorresponds to the main load direction. The term “density” is usedherein to refer to the conventional mass density.

The at least one further portion may have a further fiber orientationdifferent from the fiber orientation of the resilient portion. Thefurther fiber orientation may be chosen based on the location at whichthe at least one further portion is provided on the seat cushion body.For illustration, for a further portion located at a surface of the seatcushion body, the further fiber orientation may be directed parallel tothe surface. For a further portion located at one of the major faces ofthe seat cushion body, the further fiber orientation may be directedtransverse to the main load direction. Thereby, the faces of the seatcushion body may be configured as an adequate backing for a covermaterial.

The seat cushion body may have a first major face and a second majorface opposite to the first major face, the main load direction extendingfrom the first major face to the second major face. The at least onefurther portion may be formed on at least one of the first major face orthe second major face. Portions having a density and/or fiberorientation different from the one of the resilient portion may also beformed on both major faces. Thereby, a major face facing a seat occupantin use of the seat cushion body may be configured so as to provideadequate backing for a cover material, and the opposite major face maybe configured to provide adequate stability for attaching the seatcushion body to structural members of a seat. The major faces maygenerally extend perpendicularly to the main load direction.

The resilient portion and the at least one further portion may be offsetrelative to each other. The seat cushion body may exhibit a gradualchange in fiber orientation from the resilient portion to the at leastone further portion. Alternatively or additionally, the seat cushionbody may exhibit a gradual change in density from the resilient portionto the at least one further portion. These configurations allow the seatcushion body to be formed from loose fiber material in one bakingprocess, which is advantageous in terms of energy costs. The gradualchange in density or fiber orientation is beneficial both with regard todurability and with regard to comfort of the seat cushion body.

There may be at least one further portion distinguished from theresilient portion in terms of fiber orientation or density, which isoffset relative to the resilient portion along the main load direction.Additionally or alternative, there may be at least one further portionformed from the fibers which is distinguished from the resilient portionin terms of fiber orientation or density, and which is offset relativeto the resilient portion in a direction transverse to the main loaddirection. This allows the further portions to be positioned on the seatcushion body as required for backing a cover material, for attaching theseat cushion body to structural or other rigid members, or similar.

The seat cushion body may be formed such that fibers extend from theresilient portion into the at least one further portion. With theresilient portion and the at least one further portion being integrallyformed from the fibers, there may be some fibers extending between zonesof different fiber orientation and density, enhancing structuralintegrity of the seat cushion body.

The at least one further portion may include a functional portion formedfrom the fibers and having a density greater than the density of theresilient part. The functional portion may be formed by compressing thefiber material from which the seat cushion body is formed uponproduction of the seat cushion body. Thereby, functional portions thatmay be used for various purposes, such as lumbar support portions orattachment portions, may be integrally formed with the resilientportion. The functional portions may be formed by compression of thefiber material in specific zones of the seat cushion body.

The functional portion may be configured for attaching a seat cover tothe seat cushion body. The function portion may also be configured forattaching a rigid member, such as a structural member of a seat in whichthe seat cushion body is to be used, an adjusting mechanisms or similar,to the seat cushion body.

The fiber material may include filling fibers and binding fibers. Thefilling fibers may have a linear mass density in between 10 and 100dtex. The binding fibers may have a linear mass density in between 7 and40 dtex.

The filling fibers may have a length of preferably at least 30 mm.Filling fiber lengths may be selected to be in the range from 12-70 mm.

The seat cushion body may be formed in a unitary structure from thefibers. The seat cushion body may in particular be formed by fillingloose fiber material into a mold and supplying heat to the fibermaterial within the mold, so as to form the seat cushion body in aunitary structure which does not require separate layers ofperpendicular-laid, thermally bonded nonwovens to be joined to oneanother.

A composition of the fiber material may vary as a function of locationin the seat cushion body. The seat cushion body may include fibershaving a higher rigidity in portions of the seat cushion body where ahigh stability is desired. Alternatively or additionally, localvariations in stiffness of the seat cushion body may be attained byimplementing variations in density or variations in fiber orientation.

According to another aspect, a seat is provided which includes the seatcushion body according to any one aspect or embodiment. The seat cushionbody may be provided at a seating surface, at a backrest portion and/orat a headrest portion.

The seat may be a vehicle seat. The seat may be an automobile seat. Theseat may be a train seat. The seat may be an aircraft seat.

The seat may be a seat for office or home use.

According to another embodiment, a method of producing a seat cushionbody having a main load direction is provided. A loose fiber materialincluding fibers of at least two different types is supplied into athree-dimensional mold. The mold has a cavity and defines a directioncorresponding to the main load direction of the seat cushion body. Thefibers include thermally activable binding fibers. The fibers areoriented such that, in at least a portion of the cavity, a fiberorientation is directed along the direction corresponding to the mainload direction. Heat is supplied to the fibers filled into the mold tothermally activate the binding fibers.

Using the method, a unitary seat cushion body can be formed from thefiber material. As the method includes a step of orienting the fibersprior to supplying heat to the fibers, a seat cushion body may be formedin which, in at least one portion of the seat cushion body, the fibershave a preferential direction corresponding to the main load directionof the seat cushion body. Thereby, a desired soft feel touch and goodbreathability of the seat cushion body are attained.

The term “loose fiber material” as used herein refers to fiber materialwhich is not in the form of a nonwoven or woven fabric. The loose fibermaterial may also include agglomerations of fibers, such as fiberflocks.

The mold may have two major faces on opposite sides of the cavity, whichmay be displaceable relative to each other. By displacing the majorfaces of the mold relative to each other, the orientation and density ofthe fiber material may be changed at the major faces of the mold.Thereby, the seat cushion body may be formed with portions which aredistinguished with regard to density and/or fiber orientation from aresilient portion, in which the fibers have a preferential fiberorientation corresponding to the main load direction. Displacing themajor faces of the mold relative to each other may also assist inorienting the fibers in a portion of the cavity where it is desired forthe fibers to be oriented along the preferential direction whichcorresponds to the main load direction, so as to form the resilientportion of a seat cushion body.

The loose fiber material supplied into the mold may be compressed alonga direction parallel to the main load direction prior to supplying theheat. Thereby, the portions distinguished from the resilient portionwith regard to density and/or fiber orientation may be formed on themajor faces of the seat cushion body. The main load direction of theformed seat cushion body may generally extend in a directionperpendicular to the major faces of the seat cushion body. Inembodiments, the fiber material inserted into the mold may be compressedalong two directions transverse to each other prior to supplying theheat.

Alternatively or additionally, the loose fiber material supplied intothe mold may be compressed along a direction perpendicular to the mainload direction prior to supplying the heat. Thereby, portionsdistinguished from the resilient portion with regard to density may beformed on lateral sides of the seat cushion body.

Additionally or alternatively to locally compressing the fiber materialprior to thermal activation of the binding fibers, the fiber material orthe seat cushion body formed therefrom may be locally compressed afterthermal activation of the binding fibers. For illustration, portions ofthe seat cushion body may be compressed after thermal activation of thebinding fibers and before the seat cushion body has been allowed to cooldown to room temperature. By locally compressing portions of the seatcushion body subsequent to thermal activation of the binding fibers, forexample during the cooling process of the seat cushion body, it ispossible to reduce potential deviations of the seat cushion body shapefrom a desired final shape.

According to embodiments, the fibers may be oriented after insertioninto the mold. The fibers may be oriented using gas flows, in particularair flows.

The loose fiber material may be supplied to the mold in a gas stream. Aflow pattern of the gas stream may be controlled to orient the fiberswithin the mold. The flow pattern of the gas stream may be controlledbased on a filling level of the fiber material in the mold. To this end,the mold may be provided with through openings for the gas stream.

To orient the fiber material after insertion into the mold, the locationand/or size of an area or of areas at which gas is drawn from the moldmay be adjusted based on the filling level. Gas may be drawn from themold over major faces of the mold, which are spaced along the directionwhich corresponds to the main load direction. Gas may be drawn from themold at areas of the major faces of the mold which are respectivelydisposed lower than a current filling level of the fiber material in themold.

According to embodiments, the fibers may be oriented prior to insertioninto the mold. The loose fibers may be deposited on a conveyor and maybe oriented while being deposited on the conveyor. Orienting the fibersmay be effected using a gas stream, such as an air stream. Othertechniques for generating a parallel-laid fiber arrangement on theconveyor can be used. The oriented fibers may then be transferred fromthe conveyor into the mold such that the fiber orientation is directedalong the direction which corresponds to the main load direction in theresulting seat cushion body.

Fibers may also be accumulated prior to insertion into the mold. Adensity profile may be automatically generated in the accumulated set offibers, using pushers, gripper or other automatic tools. Theaccumulation of fibers with the density profile generated therein may betransferred into the mold. Thereby, zones having different densities orfiber orientations may be formed in the seat cushion body.

The fibers may be pre-heated to a temperature below the thermalactivation temperature of the binding fibers prior to insertion into themold. Thereby, the amount of thermal energy which has to be supplied tothe fibers after insertion of the fibers into the mold may be decreased.

Heat may be supplied to the fibers in the mold using a stream of warmgas, air or water vapor.

Variations in a density of the fiber material in the mold may beeffected by varying the amount of fiber material supplied into the moldas a function of position. Additionally or alternatively, variations inthe density of the fiber material in the mold may be effected using arobot arm. Additionally or alternatively, variations in the density ofthe fiber material in the mold may be effected by controlling the flowpattern of gas streams, for example by adjusting a location or size ofareas at which gas is drawn from the mold.

Variations in a density of the fiber material in the mold may also beeffected by using a multi-stage compression procedure. Compression toolsmay be provided which have a shape corresponding to the high densityportions of the seat cushion body.

A flow of heating medium used to supply heat to the fibers in the moldmay be controlled, for example using a gas guiding system. The flow ofthe heating medium may be controlled so as to ensure that thermalactivation of the binding fibers takes place throughout the seat cushionbody. A cooling medium may also be supplied using the gas guidingsystem.

Rigid members, such as fastening members for a seat cover, may beinserted into the mold prior to supplying heat to the fibers. Fibers maybe inserted into the mold such that the rigid members are embedded intothe fibers. Rigid members, such as fastening members for a seat cover,may also be attached to the seat cushion body after thermal activationof the binding fibers. The seat cushion body may be locally heated toembed the rigid members into the seat cushion body. Portions forattaching a seat cover may also be formed from fiber material, bylocally compressing the fiber material in pre-defined regions of theseat cushion body.

The fiber material may include the binding fibers and filling fibers.The binding fibers may be bi-component (BiCo) fibers. For illustration,the binding fibers may have a core and a coating. The core may be formedfrom polyester or polyamide. The coating may be formed from polyamide ormodified polyesters. The binding fibers may have a trilobal shape incross-section. The filling fibers may for example be formed frompolyamide or polyester. The filling fibers have a melting temperaturehigher than the thermal activation temperature of the binding fibers.The filling fibers may be straight, helical, crimped, etc., and may beused to fill the volume of the seat cushion body.

An adhesive may be supplied into the form in a controlled manner, inorder to selectively enhance the density of bonds between fibers incertain portions of the seat cushion body.

In the method, the fiber material may be supplied into the mold suchthat the composition of the supplied fiber material varies from oneportion within the mold to another portion within the mold to adjust theproperties, in particular the rigidity, of the seat cushion body in aspatially varying manner.

In the method, properties of the seat cushion body, in particular therigidity, elasticity or damping behavior of the seat cushion body, maybe controlled in a spatially varying manner. This can be attained byadjusting the composition, the density or the fiber orientation of thefiber material in a spatially varying manner.

In the method, a lumbar support portion may be formed in the seatcushion body. To this end, a zone of compressed fiber material may beformed on the B-face of the seat cushion body. The seat cushion bodyincluding the lumbar support portion may also be produced in amulti-stage process in which the lumbar support portion is formed firstfrom a fiber material which is compressed prior to supplying thermalheat thereto. The softer portions of the seat cushion body may then beproduced by supplying, in a second step, additional fiber material intothe mold, orienting the additional fiber material, and supplying heat tothe fiber material in the mold.

A process as described above in which a portion having a higher rigidityis formed in the seat cushion body may also be performed to provideattachment areas or receptacles for other rigid components. Theseattachment areas or receptacles may be used to attach components such asventilators, compressors for pneumatic seat adjustment devices orelectro-mechanical actuators to the seat cushion body.

The method may comprise removing the seat cushion body from the mold.While the seat cushion body is cooled down from the elevated temperatureat which the binding fibers are thermally activated, the external shapeof the seat cushion body may be adjusted using an auxiliary tool. Theauxiliary tool may be a mold in which the formed seat cushion body isallowed to cool down, or is actively cooled down, while mechanicalpressure is exerted onto the seat cushion body.

The auxiliary tool may be heated to smoothen and/or solidify theexternal surface of the seat cushion body. In order to fixate a desiredshape, the auxiliary tool may be cooled down. The auxiliary tool may bean auxiliary mold used for calibrating the shape of the seat cushionbody, smoothening its surface or solidifying its surface. A heatedauxiliary tool may also be used to embed additional members into theformed seat cushion body or to selectively change the density of thefibers in certain portions of the seat cushion body.

A textile or fabric made of polyester may be applied to cover the seatcushion body. The textile or fabric may be applied to the seat cushionbody after the seat cushion body has been removed from the mold.Alternatively, the textile or fabric made of polyester may be insertedinto the mold prior to filling the fiber material into the mold.

The methods according to the various embodiments may be used to producea seat cushion body according to an aspect or embodiment.

The seat cushion bodies according to various aspects and embodiments,and the methods for producing the same, may be used in various types ofseats, including seats for automobiles, aircrafts and trains and seatsfor office or home seating.

Embodiments of the invention will be described with reference to theaccompanying drawings.

FIG. 1 is a schematic cross-sectional view of a seat cushion body of anembodiment.

FIG. 2 is a schematic diagram for illustrating a method of producing aseat cushion body according to an embodiment.

FIG. 3 is another schematic diagram for illustrating a variant of themethod of FIG. 3 according to an embodiment.

FIG. 4 is a schematic cross-sectional view of a seat cushion body of anembodiment.

FIG. 5 is a schematic diagram for illustrating a method of producing aseat cushion body according to another embodiment.

Exemplary embodiments of the invention will now be described withreference to the drawings. While some embodiments will be described inthe context of specific fields of application, the embodiments are notlimited to this field of application. Further, the features of thevarious embodiments may be combined with each other unless specificallystated otherwise.

FIG. 1 is a schematic cross-sectional view of a seat cushion body 1according to an embodiment. The cross-sectional view of FIG. 1 is takenalong a plane which is perpendicular to major faces of the seat cushionbody 1 and parallel to a main load direction of the seat cushion body 1.The seat cushion body is configured to provide resilient characteristicswhen a force directed along a main load direction 2 is exerted onto theseat cushion body 1.

The seat cushion body 1 has two major faces 3, 4 which are arranged soas to be opposite to each other on the seat cushion body 1. The majorfaces 3, 4 may have an approximately planar shape, extending essentiallyperpendicularly to the main load direction 2. The seat cushion body 1may be configured such that the main load direction 2 defines a normalto the plane of the major faces 3 and 4. Protrusions or recesses (notshown in FIG. 1) may be provided on the major faces to define attachmentregions for structural or functional seat components.

The seat cushion body 1 is a unitary body which is integrally formedfrom thermally cross-linked fibers. The fiber material forming the seatcushion body may include at least two different types of fibers, namelya binding fiber and a filling fiber. The binding fiber is a fiber whichcan be thermally activated by supplying heat thereto. Upon thermalactivation, at least a portion of each binding fiber melts, therebycausing a matrix of fibers to form. Various known fiber types may beused as binding and filling fibers. The fiber material from which theseat cushion body is formed may include fibers that can be obtained fromrecycling material and/or which can be recycled in an efficient manner.The binding fibers may be bi-component (BiCo) fibers. The binding fibersmay have a thermal activation temperature which is lower than a meltingtemperature of the filling fibers. According to exemplary embodiments,the binding fibers may be BiCo fibers having a core of polyester orpolyamide, and having a coating of polyamide or modified polyester. TheBiCo fibers may have a trilobal shape in cross-section. The fillingfibers may be formed from polyester or polyamide and have a meltingtemperature higher than at least the melting temperature of the coatingof the binding fibers. The filling fibers may have a linear mass densityof preferably in between 10 and 100 dtex. The binding fibers may have apreferred linear mass density of in between 7 and 40 dtex. The fibermaterial from which the seat cushion body is formed may include morethan one type of filling fiber and/or more than one type of bindingfiber.

The seat cushion body 1 includes a plurality of different portions 5-7.The portions are distinguished from each other with regard to acharacteristic fiber orientation and/or a density of the seat cushionbody 1. There are no sharp boundaries between the different portions.Rather, the seat cushion body 1 exhibits gradual transitions in fiberorientation or seat cushion body density between the different portions.The seat cushion body 1 is distinguished from bodies which are formed byfusing pre-formed perpendicular laid fiber sheets inter alia in that itdoes not include sharp zone boundaries, which enhances durability andcomfort.

The seat cushion body 1 has a resilient portion 5. The resilient portion5 has a fiber orientation corresponding to the main load direction 2 ofthe seat cushion body. I.e., the preferential direction of the fibers inthe resilient portion corresponds to the main load direction 2 and isperpendicular to at least one major face 3 of the seat cushion body 1.Due to the formation of the fiber matrix, fiber shapes and statisticaldistributions in fiber orientation, not all fiber fibers will bedirected along the main load direction 2 in the resilient portion. Theresilient portion 5 may be considered to have a fiber orientation alongthe main load direction 2 if more than 50% of the fibers arerespectively oriented at an angle of less than 45° to the main loaddirection 2. In other words, in the resilient portion 5, the majority offibers is disposed at angle of more than 45° relative to the plane ofthe major face 3.

The fiber configuration in the resilient portion 5 is schematicallyindicated at the inset 15. As seen in the inset 15, a majority of thefibers in the resilient portion 5 may be oriented at an angle of lessthan 45° to the main load direction, and the fiber spacing may besufficiently large so as to allow the fibers to deflect when a load isdirected along the main load direction 2. Cross-linking fibers, whichinterconnect the fibers which are mainly disposed parallel to the mainload direction 2, allow a fiber matrix to be formed in the resilientportion 5.

The seat cushion body 1 also includes further portions 6, 7 disposed atthe major faces 3 and 4, respectively. The further portions 6 and 7,respectively, are distinguished from the resilient portion 5 with regardto at least one of fiber orientation or seat cushion body density. Inthe seat cushion body 1 of FIG. 1, the fibers in the further portions 6and 7 respectively have a preferential direction parallel to the planeof the major face at which they are disposed. The density of the seatcushion body at the major faces 3 or 4 may be greater than a density inthe resilient portion 5.

The fiber configuration in the further portion 6 disposed at the majorface 3 is schematically indicated at the inset 16. As seen in the inset16, a majority of the fibers in the face portion 6 may be oriented at anangle of less than 45° to the plane of the major face 3, and the fibersmay have a packing density greater than in the resilient portion 5. Thefurther portion 7 disposed on the other major face 4 may have aconfiguration, with regard to fiber orientation and seat cushion bodydensity, which is similar to the one of the portion 6.

As has been indicated above, the seat cushion body 1 is formed in aunitary manner, and there are gradual transitions in fiber orientationand density between the resilient portion 5 and the further portions 6and 7, respectively. The seat cushion body 1 includes a transitionportion 8 which is disposed in between the resilient portion 5 and thefurther portion 6 on the major face 3. In the transition portion 8, thefiber orientation varies gradually from the fiber orientation of theresilient portion 5 to the fiber orientation of the further potion 6 onthe major face 3, and the density of the cushion body varies graduallyfrom the density of the resilient portion to the density of the furtherportion 6 on the major face 3. The fiber configuration in the resilientportion 8 is schematically indicated at the inset 17.

The seat cushion body 1 includes a transition portion 9 which isdisposed in between the resilient portion 5 and the further portion 7 onthe major face 4. In the transition portion 9, the fiber orientationvaries gradually from the fiber orientation of the resilient portion 5to the fiber orientation of the further potion 7 on the major face 4,and the density of the cushion body varies gradually from the density ofthe resilient portion 5 to the density of the further portion 7 on themajor face 4.

The seat cushion body 1 is formed in a unitary manner from the fibermaterial which includes binding and filling fibers. While the seatcushion body 1 has portions distinguished from each other with regard tofiber orientation and/or seat cushion body density, the seat cushionbody 1 is homogeneous in the sense that there are no sharp zoneboundaries between portions of different fiber orientation and/or seatcushion body density. The seat cushion body 1 thus formed as a unitarybody has a height 12 which may be greater than 4 cm. The resilientportion 5 having a height 11 may be disposed so as to be spaced fromboth major faces 3 and 4.

Fibers may extend between the different portions of the seat cushionbody. For illustration, at least the filling fibers may have a length ofpreferably more than 30 mm. For further illustration, at least thefilling fibers may have a length of preferably less than or equal to 60mm. At least some of the fibers may extend from the resilient portion 5into the further portion 6 on the major face 3 or into the furtherportion 7 on the major face 4.

In the seat cushion body 1, the resilient portion 5 having the fiberorientation along the main load direction 2 provides good ventilationand resiliency. With the seat cushion body 1 being formed in a unitarymanner from thermally cross-linked fibers, good durability and comfortare attained.

Various modifications of the seat cushion body 1 can be implemented inother embodiments. For illustration, while portions 5-7 of differentfiber orientation and density are illustrated in FIG. 1, there may beadditional or alternative portions which are distinguished from theresilient portion 5 with regard to fiber density. While the furtherportions 6 and 7 on the major faces 3 and 4, respectively, are offsetfrom the resilient portion 5 along the main load direction 2, furtherportions having a fiber orientation or density different from the one ofthe resilient portion 5 may also be offset from the resilient portionalong a direction perpendicular to the main load direction 2. Forillustration, further portions having a density greater than that of theresilient portion 5 may be provided on minor faces of the seat cushionbody, which extend parallel to the main load direction 2.

FIG. 2 is a schematic representation for explaining a method ofproducing a seat cushion body according to an embodiment. The seatcushion body is formed as a unitary body from a thermally cross-linkedfiber material. The method may be used to produce a seat cushion bodyaccording to an embodiment, for example the seat cushion body of FIG. 1.Various stages of the method are illustrated at 31, 32 and 33.

The method utilizes an apparatus 20 for producing the seat cushion body.The apparatus 20 includes a mold, which has a first mold 21 and a secondmold 22. The first mold 21 and the second mold 22 may respectively beformed from a perforated material, e.g., from perforated metal sheets.The first mold 21 and second mold 22 may have a three-dimensionalinterior shape which corresponds to the shape of major faces of the seatcushion body. The apparatus 20 further includes gas guiding devices 23and 23′ for drawing gas from a volume defined by the first mold 21 andsecond mold 22. The gas guiding device 23 may include a controllableguiding assembly 24. The controllable guiding assembly 24 is configuredsuch that gas may be selectively drawn into the gas guiding device 23over various different areas of the guiding assembly 24. The locationand size of the area at which gas is drawn from the volume 26 defined bythe first mold 21 and the second mold 22 may be controlled via theguiding assembly 24. Similarly, the gas guiding device 23′ may include acontrollable guiding assembly 24′. The controllable guiding assembly 24′is configured such that gas may be selectively drawn into the gasguiding device 23′ over various different areas of the guiding assembly24′. The location and size of the area at which gas is drawn from thevolume 26 defined by the first mold 21 and the second mold 22 into thegas guiding device 23′ may be controlled via the guiding assembly 24′.The apparatus 20 also includes a supply device 27 for supply fibermaterial. The supply device 27 may include a tube, which may supply thefiber material entrained in a gas flow into the mold 21, 22. The moldformed by the first mold 21 and the second mold 22 defines a direction28 along which the first and second moldy 21, 22 are spaced. Thedirection 28 corresponds to the main load direction of the seat cushionbody which is formed using the method.

At 31, the first mold 21 and second mold 22 are disposed at a firstdistance. Loose fiber material, which includes binding fibers andfilling fibers, is supplied into the mold 21, 22 via the supply device27. The loose fiber material may be supplied in the form of fiberflocks. The fiber material is entrained in a gas stream 29, which issupplied to the mold 21, 22. When the fiber material is supplied intothe mold 21, 22 so as to cover the mold bottom, gas may be drawn intothe gas guiding devices 23 and 23′ at locations which are generallydisposed at the lower end of the molds 21, 22.

At a later stage illustrated at 32, fiber material has been filled intothe mold up to a level 34. At this stage, fiber material may still besupplied into the mold 21, 22 via the supply device 27. The fibermaterial may be entrained in a gas stream supplied by the supply device27. Gas may be drawn into the gas guiding devices 23 and 23′ atlocations which are generally disposed lower than the filling level 34of the mold. As the filling level 34 rises, the location at which gas isdrawn from the volume enclosed by the molds 21 and 22 may be controlledusing the controllable guiding assemblies 24 and 24′, respectively. Forillustration, the guiding assemblies 24 and 24′ may respectively includea plurality of flaps which are spaced from each other at least along thevertical direction, and flaps may be opened and closed in a controlledmanner depending on the filling level 34. Using the controllable guidingassemblies 24 and 24′, the flow pattern 35 of a gas stream may becontrolled.

The gas stream 35 may be controlled such that the gas stream passingthrough the mold has a velocity component along the direction 28, whichcorresponds to the main load direction of the formed seat cushion body.The gas stream may be controlled such that, at least in a part of thevolume 26 enclosed by the first and second molds 21, 22, the velocitycomponent of the gas stream 35 parallel to the direction 28 is muchgreater than the velocity component which is perpendicular to thedirection 28 and which extends parallel to the major faces (i.e., thevelocity component which is perpendicular to the drawing plane in FIG.2).

By controlling a flow pattern of the gas stream such that it passesthrough the fiber material deposited in the mold with a significantvelocity component parallel to the direction 28, fibers may be orientedin the mold such that they have the direction 28 as a preferentialdirection.

At 33, fiber material has been filled into the mold up to a level 34,and no further fiber material is supplied. The first mold 21 and thesecond mold 22 are displaced relative to each other along the direction28, as illustrated at 36. The first mold 21 and the second mold 22 maybe displaced relative to a laboratory frame of reference. By displacingthe first mold 21 and the second mold 22 relative to each other,portions of enhanced density may be formed within the volume 26 enclosedby the first and second molds 21, 22. Displacing the first mold 21 andthe second mold 22 relative to each other may also assist inestablishing a fiber orientation parallel to the inner surfaces of thefirst mold 21 and the second mold 22 in a region adjacent to the innersurfaces, and/or in establishing a fiber orientation parallel to thedirection 28 in a portion of the volume 26 which is spaced from theinner surfaces of the first mold 21 and the second mold 22.

After the first mold and the second mold have been displaced relative toeach other, so as to establish a desired profile in fiber orientationsor in density within the fiber material disposed within the mold, heatmay be supplied to the fiber material. By supplying heat, the bindingfibers may be thermally activated. A fiber matrix of thermallycross-linked fibers may be formed by thermal activation of the bindingfibers.

Heat for thermal activation of the binding fibers may be supplied invarious ways. As illustrated at 33 in FIG. 2, a stream 36 of hot gas maybe supplied into the mold. The gas guiding devices 23 and 23′ may beused to direct the hot gas to portions of the fiber material disposedwithin the mold 21, 22 in a defined manner. The amount of hot gassupplied to various regions within the mold 21, 22 may be controlledbased on, for example, the density or thickness of the seat cushion bodyin the respective regions.

The fiber material may be pre-heated to elevated temperatures, which arelower than the thermal activation energy of the binding fibers, when thefiber material is inserted into the mold. Thereby, the amount of energyrequired to thermally activate the binding fibers after the mold hasbeen filled up to a desired level may be reduced.

The seat cushion body formed within the mold 21, 22 may be allowed tocool down. Another stream of gas, such as gas having room temperature orgas cooled to a temperature below room temperature, may be guidedthrough the seat cushion body formed within the mold 21, 22.

It will be appreciated that only one heating process is sufficient toproduce the three-dimensional seat cushion body from loose fibermaterial, when using the method illustrated in FIG. 2. This is incontrast to methods in which plural sheets of perpendicular laid fibers,produced by the Struto method, are stacked and bonded to each other.Generally, plural heating steps are required to produce the sheets ofperpendicular laid fibers using the Struto method.

Additional processing steps may be performed in the method. Forillustration, after forming the three-dimensional seat cushion body inthe mold 21, 22, the seat cushion body may be inserted into an auxiliarymold to provide the seat cushion body with its final exterior shape, orto further solidify or smoothen its exterior surface. The seat cushionbody may be inserted into the auxiliary mold while it is still atelevated temperatures or the auxiliary mold may be heated.

Functional elements may be inserted into the mold 21, 22 prior to, or inparallel with, filling the mold 21, 22 with the fiber material. Forillustration, attaching members for a seat cover may be removablyattached to the first mold 21 or the second mold 22. The attachingmembers may be formed from a metal. The attaching members are covered bythe fiber material when the fiber material is supplied into the mold andare embedded into the seat cushion body upon thermal activation of thebinding fibers.

Portions having a density greater than a density of the resilientportion may be selectively formed by controlling the density of fibermaterial supplied into the mold as a function of supply position, byselectively compressing the fiber material supplied into the mold, or bypost-processing. For illustration, a heated tool my be used to locallyincrease the density of the seat cushion body after it has been removedfrom the mold 21, 22. Thereby, a portion of the seat cushion body may beprovided with a high density, so that a seat cover material can befastened on the seat cushion body at the high density portion.

FIG. 3 shows a top view of the mold having the first mold 21 and thesecond mold 22 of FIG. 2. The top view is taken along the directionindicated at line III-III in FIG. 2.

As illustrated in FIG. 3, the fiber material supplied into the mold maybe compressed not only in one direction, but rather along severaldirections. As shown at 33, the first mold 21 and the second mold 22 maybe displaced relative to each other in order to produce regions having ahigher density in the fiber material, the higher density regions beingdisposed along the inner surfaces of the first mold 21 and the secondmold 22.

Subsequently, the fiber material which has been inserted into the moldmay be compressed on minor lateral faces of the seat cushion body. Tothis end, moveable portions 37 and 38 may be displaced in a direction 39perpendicular to the direction 28, which corresponds to the main loaddirection of the seat cushion body.

After the fiber material has been compressed in at least two directions,as illustrated in FIG. 3, heat may be supplied to the fiber material soas to cause thermal activation of the binding fibers.

According to further embodiments, the method may include compressing thefiber material inserted into the mold in at least three orthogonaldirections prior to supplying heat to the fiber material.

FIG. 4 is a schematic cross-sectional view of a seat cushion body 41according to another embodiment. The cross-sectional view is taken in aplane which is orthogonal to the main load direction of the seat cushionbody 41. I.e., the main load direction of the seat cushion body 41 isperpendicular to the drawing plane of FIG. 4.

The seat cushion body 41 is formed as a unitary body from a fibermaterial which includes binding fibers and filling fibers. The fibermaterial may be selected as has been explained with reference to FIG. 1.The seat cushion body 41 may be formed using any one of the methodsdescribed herein, such as the method of FIG. 2.

The seat cushion body 41 includes two resilient portions 42 and 43spaced from each other in a direction perpendicular to the main loaddirection. The two resilient portions 42 and 43 may be arranged suchthat, in use of the seat cushion body 41, each one of the resilientportions 42 and 43 supports a thigh. Each one of the two resilientportions 42 and 43 has a fiber orientation corresponding to the mainload direction. I.e., in each one of the two resilient portions, thefibers have a preferential orientation which corresponds to the mainload direction. For illustration, more than 50% of the fibers in theresilient portions 42 and 43 may be oriented at an angle of less than45° relative to the main load direction.

The seat cushion body 41 includes further portions 44-47 whichrespectively have a fiber orientation and/or a density different from afiber orientation and/or a density of the resilient portions 42 and 43.For illustration, the further portions 44-47 may be formed to have adensity greater than a density of the resilient portions 42 and 43,respectively. The further portions 44-47 may be disposed to extend alonglateral sides of the seat cushion body. The further portions 44-47 maybe configured to have higher rigidity than the resilient portions 42 and43, so that structural seat components or functional entities may beattached to the seat cushion body. Examples for functional entitiesinclude actuating elements, ventilation devices, components of a heatingor cooling assembly or other components.

The seat cushion body 41 further includes transition portions disposedin between the resilient portions 42 and 43 and the further portions44-47. In the transition portions, the density and/or fiber orientationvaries gradually. There is a gradual transition in density and/or fiberorientation in the seat cushion body, without there being sharp zoneboundaries associated with an abrupt change in fiber orientation and/ordensity. The seat cushion body 41 may be homogeneous in the sense thatit does not have zone boundaries at which the fiber orientation and/ordensity changes discontinuously.

According to various embodiments, portions of the seat cushion body maybe provided with a desired density profile so as to accommodatefunctional needs. For illustration, as has been explained with referenceto the seat cushion body 1 of FIG. 1, a portion of the seat cushion bodyat a major face (A face) of the seat cushion body may be provided with afiber orientation in which most fibers extend parallel to the face, soas to provide adequate backing for a seat cover material. Alternativelyor additionally, lateral faces or the opposite major face (B face) oflateral side faces of the seat cushion body may be provided with aportion of fiber material having an increased density, so as to allowstructural seat members or functional units to be attached to the seatcushion body.

FIG. 5 is a schematic representation for explaining a method ofproducing a seat cushion body according to another embodiment. The seatcushion body is formed as a unitary body from a thermally cross-linkedfiber material. The method may be used to produce a seat cushion bodyaccording to an embodiment, for example the seat cushion body 1 of FIG.1 or the seat cushion body 41 of FIG. 4. Only initial stages of themethod are illustrated at 51 and 52 in FIG. 5. The components of theapparatus 20 are operative as described with reference to FIG. 2.

At 51, fiber material is supplied into the mold in a gas stream. The gasmay be drawn from the cavity 26 defined by the first mold 21 and thesecond mold 22. The gas stream may be drawn into the gas guiding device23′ at a location which is controlled using the controllable guidingassembly 24′. The flow of the gas stream 53 is directed such that thegas stream passes through the second mold 22 at a position spaced fromthe bottom of the second mold 22. Thereby, a local accumulation of fibermaterial 54 is effected. The inner surface of the second mold 22, incombination with the gas stream 53, assists in orienting the fibers inthe local accumulation 54 so that the fibers are preferentially disposedparallel to the inner surface of the second mold 22. The process may berepeated for different locations on the inner surface of the first mold21 and/or the second mold 22, so as to generate a pattern of regionshaving a desired density along the inner faces of the first and secondmolds 21, 22. Thereby, the seat cushion body may be provided with highdensity regions on its exterior.

At 52, fiber material is supplied into the mold in a gas stream. The gasstream may be drawn into the gas guiding device 23′ at a location whichis controlled using the controllable guiding assembly 24′ and which isoffset from the location at which gas had previously been drawn from themold in stage 51. Thereby, a local accumulation of fiber material 56 iseffected. The inner surface of the second mold 22, in combination withthe gas stream 55, assists in orienting the fibers in the localaccumulation 56 so that the fibers are preferentially disposed parallelto the inner surface of the second mold 22.

The fibers accumulated at 54 and 56 may be kept in position using anadhesive material, or by heating the fiber material so as to thermallyactivate the fibers in the accumulation 54 and/or the accumulation 56.

After portions of desired density and/or fiber orientation have beenformed as described with reference to FIG. 5, the method may continue asdescribed with reference to FIG. 3. Additional fiber material may besupplied into the mold. The fibers may be oriented. Gas may be drawnfrom the cavity defined by the first mold and the second mold at alocation which is disposed lower than a current filling level of thefiber material in the mold in this process. Heat may be supplied to thefiber material, so as to thermally activate the binding fibers. A fibermatrix of thermally cross-linked fibers is thus formed. The resultingthree-dimensional seat cushion body is formed as a unitary body from thefiber material.

While seat cushion bodies according to various embodiments have beendescribed, various modifications may be implemented in otherembodiments. For illustration, while integrally formed seat cushionbodies have been described which include a resilient portion and atleast one further portion distinguished from the resilient portion withregard to fiber orientation and/or mass density, the at least onefurther portion may be distinguished from the resilient portion alsowith regard to the composition of the fiber material from which it isformed. The seat cushion body according to such an embodiment mayexhibit a profile in composition of the fiber material from which it isformed. The profile in the composition of the fiber material may beselected such that portions having an increased rigidity, as compared tothe resilient portion, may be formed at desired locations.

For further illustration, additional materials may be supplied into themold prior to thermal activation of the binding fibers. In exemplaryembodiments, adhesive material may be selectively supplied into themold, so that the adhesive material is concentrated at pre-definedlocations within the cavity defined by mold. The adhesive material maybe selectively supplied to locally enhance the density of bonds betweenfibers.

While seat cushion bodies have been described which allow structuralseat components or other functional components to be attached to theseat cushion body, the seat cushion body may also be formed such thatsupport or comfort functions which are normally implemented with the aidof separate components may be integrated into the seat cushion bodyitself. For illustration, a lumbar support portion having an increaseddensity may be formed.

While methods of producing a seat cushion body have been described inwhich the fibers are oriented after insertion into the mold, fibersoriented along a preferential direction may also be formed prior toinserting the fibers into the mold. The oriented fibers may be formed asparallel laid fibers on a conveyor. The fibers may be automaticallytransferred into the mold. The fibers may be inserted into the mold suchthat their preferential direction corresponds to the main load directionof the seat cushion body formed within the mold. I.e., the fibers may betransferred such that their preferential direction is perpendicular tothe major faces defined by the inner surfaces of the mold.

The seat cushion bodies according to embodiments may be integrated intoa wide variety of seats. Exemplary seats in which the seat cushionbodies may be used include automobile seats, train seats, aircraftseats, seats for home use and seats for office use. The seat cushionbodies according to various embodiments may further be used on variouscomponents of the seat. For illustration, a seat cushion body may beused at a seat portion which receives a person's thighs, at a backrestportion supporting a person's back, or at a headrest portion or othercomponent where cushioning is desired.

The invention claimed is:
 1. A method of producing a seat cushion body,said seat cushion body having a main load direction, said methodcomprising: supplying a loose fiber material including fibers of atleast two different types into a three-dimensional mold in a gas stream,said mold having a cavity and defining a direction corresponding to saidmain load direction of said seat cushion body, said fibers includingthermally activable binding fibers; orienting said fibers such that, inat least a portion of said cavity, a fiber orientation is establishedwhich is directed along said direction corresponding to said main loaddirection; and supplying heat to said fibers filled into said mold tothermally activate said binding fibers, wherein a flow pattern of saidgas stream is controlled to orient said fibers within said mold.
 2. Themethod of claim 1, wherein said flow pattern of said gas stream iscontrolled based on a filling level of said fiber material in said mold.3. A method of producing a seat cushion body, said seat cushion bodyhaving a main load direction, said method comprising: supplying a loosefiber material including fibers of at least two different types into athree-dimensional mold, said mold having a cavity and defining adirection corresponding to said main load direction of said seat cushionbody, said fibers including thermally activable binding fibers;orienting said fibers such that, in at least a portion of said cavity, afiber orientation is established which is directed along said directioncorresponding to said main load direction; supplying heat to said fibersfilled into said mold to thermally activate said binding fibers; andcompressing said loose fiber material supplied into said mold along saiddirection prior to supplying said heat and along a directionperpendicular to said direction prior to supplying said heat.
 4. Themethod of claim 3, wherein said mold includes a first mold and a secondmold enclosing said cavity, said method comprising effecting a relativedisplacement of said first mold and said second mold to compress saidloose fiber material.